Enable completions and add description for lfcd.fish and simplify the…

… code (#1503)

* Enable completions and add description for lfcd.fish

A simple addition of `--wraps=lf` to the function definition will enable the standard lf completions to be used for `lfcd` function as well.

* Simplify lfcd.fish

* lfcd.fish: unquote $argv

* lfcd.fish: further simplify

* lfcd.fish: cd only on clean exit

* lfcd.fish: further simplify and add a coment on quoting semantics

* lfcd.fish: amend comment style

etc/lfcd.fish

@@ -11,17 +11,8 @@
 #
 # You may put this in a function called fish_user_key_bindings.
 
-function lfcd
-    set tmp (mktemp)
-    # `command` is needed in case `lfcd` is aliased to `lf`
-    command lf -last-dir-path=$tmp $argv
-    if test -f "$tmp"
-        set dir (cat $tmp)
-        rm -f $tmp
-        if test -d "$dir"
-            if test "$dir" != (pwd)
-                cd $dir
-            end
-        end
-    end
+function lfcd --wraps="lf" --description="lf - Terminal file manager (changing directory on exit)"
+    # `command` is needed in case `lfcd` is aliased to `lf`.
+    # Quotes will cause `cd` to not change directory if `lf` prints nothing to stdout due to an error.
+    cd "$(command lf -print-last-dir $argv)"
 end